I completely understand where your tone is coming from. Why (on earth) is Sencha setting a flag startCollapsed to false intentionally. Your solution kicks ass. For anybody trying the same. Really, it's nothing more than overriding the entire processStore method of Ext.grid.feature.GroupStore. And make sure to just comment out the one line above marked with // DISABLED ONLY THIS =>>>

This solution is still needed with Ext JS 4.2.1 and it has proven to solve the problem with this version.